I having a bug here... a big one.
When my put 1 portal and don t put another, normally it get "closed". But the problem is that when my put 2 portals they get closed...
I called the steam suport, but the problem doe not get solved.He(or she) asked me some questions, but nothing solved, the bug occurs in portal 2, portal 1 and portal prellude, and when playing coop my partner see my portals open and my see my and him portal closed...
Someone knows how to fix it?

I restart the game many times, create new saves, pass of chapters, play coop, and my doe not reinstall because later my install others portals game and the same bug apeared... So my count like a "reinstall" because my install other thing. And yes,, I called steam suport, just see my post...

It might just be that your specific computer is running either specs that aren't good enough or advanced enough, or a program that is getting in the way, or you just need to fiddle with it.

If the game is ALREADY ON the lowest settings, your rig kinda sucks if it cannot even display the portals.

Can you perhaps show a screenshot of what you are looking at when the game runs? Like an ACTUAL screenshot, since the link you posted leads to Steam Support and not to a screenie? Post it in your Steam library's screenshots.

You didn't answer my earlier question about if you did the things that were shown in that other thread you linked to us. Also, if your game did work, and now it doesn't, that is a big clue that something IS wrong with your computer. Not that you should defend it as it falls apart. CHECK IT for airflow and cool temperature, test the RAM, make sure you're not almost out of hard drive space.

These are basic issues that could be the cause of the problem. Don't just say no, because at this point it's far more likely to be a problem with your computer than a problem with either Steam or Portal.